<template>
  <div class="spec-preview" ref="container">
    <!-- 图 -->
    <img :src="skuDefaultImg" />
    <!-- 事件区域 -->
    <div class="event" @mousemove="moveMask"></div>
    <!-- 大图区域 -->
    <div class="big" ref="big">
      <img :src="skuDefaultImg" ref="bigImg" />
    </div>
    <!-- 蒙版 -->
    <div class="mask" ref="mask"></div>
  </div>
</template>

<script>
export default {
  name: "Zoom",
  data() {
    return {
      clientX: 0,
      clientY: 0,
    };
  },
  props: {
    skuDefaultImg: String,
  },
 
  methods: {
    moveMask(e) {
      const { mask, container, big, bigImg } = this.$refs;
      let all = {
        left: container.getBoundingClientRect().left,
        top: container.getBoundingClientRect().top,
      };
      let maskL = {
        left: e.clientX - all.left - mask.offsetWidth / 2,
        top: e.clientY - all.top - mask.offsetWidth / 2,
      };
      const maxSet = container.clientWidth - mask.offsetWidth;
      if (maskL.left < 0) maskL.left = 0;
      if (maskL.left > maxSet) maskL.left = maxSet;
      if (maskL.top < 0) maskL.top = 0;
      if (maskL.top > maxSet) maskL.top = maxSet;
      mask.style.left = maskL.left + "px";
      mask.style.top = maskL.top + "px";
      const scale =
        (bigImg.clientWidth - big.offsetWidth) /
        (container.clientWidth - mask.offsetWidth);
      bigImg.style.left = -maskL.left * scale + "px";
      bigImg.style.top = -maskL.top * scale + "px";
    },
  },
};
</script>

<style lang="less">
.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;

  img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(0, 255, 0, 0.3);
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  .event:hover ~ .mask,
  .event:hover ~ .big {
    display: block;
  }
}
</style>